1. Field of the Invention
The invention relates first of all to a process for coupling at least one hollow fiber to a microfluidic network, the microfluidic network having at least one channel which is open on the top side and in which the hollow fiber is inserted with one end. Furthermore the invention relates to a device for implementing this process, specifically a microfluidic system consisting of a microfluidic network with a microstructure carrier and a coupled microfluidic hollow fiber which is inserted with one end in the channel and which discharges on the face side into the channel.
2. Description of Related Art
In Microsystems engineering, connecting components with microstructured surfaces to one another by cementing is known. With these processes, often only two planar parallel surfaces are cemented to one another. In doing so, cement flows in one plane. In order to cement to one another the components to be joined with sufficient positioning accuracy, they must be temporarily fixed relative to one another by another technique before the actual cementing process. This is difficult when several parts are to be fluidically tightly cemented to one another on different planes, especially when one of the components which is to be cemented to another is comparatively movable, especially for a hollow fiber.
Allowing a cement which is liquid in the processing state to flow into narrowly dimensioned channels, grooves or other function areas by using capillary forces is incidentally known in and of itself (see especially, Wolfgang Menz, Juergen Mohr: Microsystems Engineering for Engineers, VCH Verlagsgesellschaft mbH, 2nd edition, 1997, ISBN 3-527-29405-8).
German Patent DE 34 08 783 C2 and its counterpart U.S. Pat. No. 4,657,341 relate to a connecting element for optical fibers, the fibers being cemented into microstructured grooves.
International Patent Application Publication WO 98/25065 A1 and its counterpart U.S. Pat. No. 6,290,791, which form the starting point of this invention, disclose a microfluidic network having at least one hollow fiber which is cemented into a channel. The hollow fiber is inserted into the channel, the channel is covered by a cover plate, and then a cement is supplied, if necessary, via a lateral feed, which cement, if necessary, can be cured by UV radiation especially in the area of the end face of the hollow fiber and the hollow fiber is cemented in the channel. However, the known process does not ensure optimum positioning of the hollow fiber in the channel. The problem is especially that excess cement can undesirably penetrate into the inserted open end of the hollow fiber and can seal it.
International Patent Application Publication WO 97/29394 A1 and its counterpart U.S. Pat. No. 5,985,086 relate to cementing an optical fiber into a V-groove, the cement being supplied via two opposing lateral feed channels to the V-groove so that complete jacketing of the fiber with cement can be avoided.
International Patent Application Publication WO 01/86154 A1 discloses cementing of a capillary tube into a channel, the inside surface of the channel and the outside surface of the capillary tube being kept in a predetermined orientation and at a predetermined distance relative to one another in order to achieve the desired capillary effect between them and cement being supplied in a matched amount to fill the intermediate space. However, it is difficult and can be complex to determine and maintain this amount. The problem is especially that excess cement can undesirably penetrate into the inserted open end of the hollow fiber and can seal it.
French Patent Publication FR 2 813 073 A1 discloses the cementing of capillary tubes in V-shaped grooves of a microstructure, several capillary tubes being introduced by means of a holding element into grooves which project relative to the cover and being pushed to under the cover and then being cemented in the grooves by means of cement. It is a particular problem that excess cement can undesirably penetrate into the inserted open end of the hollow fiber and can seal it.